Method of receiving electrical oscillations



Jan. 31, 1928.

1,657,567 H. D. CURRIER METHOD OF RECEIVING ELECTRICAL OSCILLATIONS Filed Nov. 12, 1924 embodying the invention in which p acity Patented Jan. 31, 1928.

UNITED STATES.

PATENT a a HIRAM D. CURRIEB, OF CHICAGO, ILLINOIS, ASSIGNORB 'IOv KELLOGG SWITGHBOARI) AND SUPPLY COMPANY, OF CHICAGO," ILLINOIS, A CORPORATION '0FILL'INOIS.1

METHOD or nncnryrne ELECTRICAL; oscrnrinrrons Application filed November 12, 1924. serial fiot 749,366.

invention relates to wireless telegraphy and telephony and resides in; certain novelicircuit arrangements for such systems, and in the accompanying drawing my inven' tionis shown as employed for the reception of" signals. The invention however is not limited to receiving purposes and its objects are to provide a novel and improved organization of the elements comprising such a system and which provides an arrangement affording sharpness of tuning, power and clearness in respect of the signals received.

The accompanying drawing diagrammatically shows a preferred organization 2 illustrates the antenna connected to an. auto-translormer AT. I provide a pair of switches 23 and ttor the auto-transformer so that the number of turns both in the primary and secondary ofthe same may be varied to make the same operate etficiently over the wave band of oscillations to which the receiving circuit is adapted to respond. Across the auto-transforme13 I provide a variable 'cafor turning the same. With my arrangement as shown, I provide a radio frequency audion tube EFT, a detector tube DT and two other audion tubes AT and AT for so called audio frequency amplification. The radio frequency tube is connected to the detector tube through an air core transformer ACT which has a substantially one to one ratio between I the primary and secondary thereof. I tune the secondary oi the transformer ACT by meansroi' a variable capacity 6, the detector tube DT being coupled to the tube AT by means of aniron core transformer AFTand the tube AT- is related to the tube AT by means of an iron core transformer AFT; I provide the usual grid condenser andgridlealr 7' and 8 which are connectedto the grid member of the detector tube -DT. I

I have shown a separate variable resistance for controlling the current flow of the filaments for each of the audion tubes, but it is under'stood'that one rheostat may be used for two or more tubes; A low voltage battery 9 is provided. to1"furnishing'current to'heat the filament-s ofthe audion' tubes. I provide higher voltage batteries lOy 11' and 12 foriurnishing current to the plates of the audion tubes. At 14, I provide an oscillation receiving device which is {shown in the drawing as a pairjofreceivers but may be any other desired receiving device. I

have found. it desirable in my arrangement to provide substantially I a zero potential upon the grids of the tubesRFT and-DI;

To accomplish this arrangement,.I- haveprovided a pair of: coils 15-and 16 bridged across the battery 9, the central point of these coils being connected to the grid returns of the tubes EFT and DTr Iiffltound desirable, a

variable device such as a potentiometer may be used in place of the arrangement which I have just described. To provide a path that the incoming oscillations will readily travel,

I have provided a condenser 17 bridged from point 20 todground at 21. This condenser is 013a size to readily pass the high frequency incoming oscillations.

I have determined that in an arrangement which is adapted to receive oscillations that vary a great deal intheirtrequency, that is to receive oscillations of diifere'ntjwave lengths, thatit is necessary to have the number of turns of the primary and secondary oi? the air core auto transformer AT variable to receivethe maximum. and most efficient operation of the same.- Likewismil' [indtl'iat where it is clesiredto receive incoming oscillations that do not vary 'agreat deal from interfering oscillations that I can very nicely receive the desired oscillations without-inter .terencefrom interfering oscillations byregulating thenumber ofturns ofthe autotransformer in the primary and secondaryof the same."

I further provide a. condenser- '22 connected from :one terminal ofthej audio fre quency transformer AFT tothe grounded terminal of the battery9ffor the usual and well known purpose. I find-that'by having an efficient coupling between the antenna '2 and the grid of the radio frequeneyitube and EFT in the nature of the auto transformer AT, that the rheostat plays an important part in bringing in the signal with maximum sharpness and volume.

When an incoming oscillation is to be received the switches 3 and lof the auto transformer are so set as to receive the best coupling. effect between the primary and secondary thereof that the radio frequency tube will readily handle. The condensers 5 and 6 are then operatedto tune the coils to the wavelength or to the cycle of the inconr ing oscillations. The rheostat controlling the heating current ot' the filament of the radio frequency tube RFT may then be operatcd to change the current flow through the filament of said tube until the signal is received in the desired manner. The two condensers 5 and G and the rheostat R form the main tuning units of the zu'rangement, the switches 3 and 4: being set according to the wave lengths of the oscillations that it is desired to receive.

The incoming oscillations are effective on the audion tube EFT in the usual manner by way of the grid element, so that the potential changes operate the grid element through the medium of the auto transformer AT.

The selected oscillations are then supplied to the primary of the air core transformer ACT by the plate of the radio frequency tube. The secondary of the transformer ACT being tuned permits the selected repeated oscillations to act upon the grid of the detector tube DT, which in return repeats the in1- pulses through the primary of the audio transformer AFT and from the secondary of the audio frequency transformer AFT through the tubes AT and AT by way of the audio frequency transformer AFT, to the receiving device 14. By having the primary of the. air core transformer ACT of substantially the same number of turns as the secondary thereof, and by having an ellicient coupling between the aerial and the radio frequency tube RFT, the grid of the detector tube is supplied with strong potential changes, and, by using a zero potential upon the grids ot the first two tubes I provide a system which is extremely cllicicnt and produces rcniarkablc results. The transl'm'mcrs All and AC'lare pre'le ably ot the type disclosed in my co-pending application, S. N. 7111,4651, filed the 18th day of October, 1924:.

On account of the very high frequency of the oscillatory currents involved in systems of this character and their tenuity together with. the sensitively balanced effects that 'st when such systems are operated, it is, as is well known, quite ditficult to ascertain the precise actions and re-actions involved as applications of tests sometimes render inelfective the very matters that it is sought to consider.

The preceding description and explanation will enable anyone shillelfl in the art to prac tice the invention and the analysis given is believed to indicate the principal etl'ects involved in the results obtained.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

l. A receiving circuit including a transformer having a continuous winding, one end of the same being permanently coimectcd thru a fixed condenser to earth, an oscillation receiving device, means for variably associating said oscillation receiving device with turns of said transformer, an audion tube having a control element and an anode, means for variably associating said control element with other turns of said transformer, said two means functioning to provide a variable turn ratio between the input circuit including said oscillation receiving device and the output circuit including said turns of said transformer, a variable condenser permanently connected to said grid control element and said fixed condenser across the turns in the input and output circuits of said transformer but adapted to be variably associated with the winding of said transfornuzr depending upon the association of said cow trol element with said transformer, a second transtorn'ier having a primary connected to the anode of said audion tube, a seccmdary winding for said second transformer, a uni able condenser connected across said secondary winding for resonating the same to the desired frequency, and a second audion tube connected to said secondary winding for receiving oscillations from said secondary winding and adapted to detect and relay the same to a reproducer.

2. A receiving circuit including a trans former having a continuous winding, a fixed condenser and a. potentiometer pern'laneiitly connected to one end of the winding ot said transformer, an oscillation receiving llOVlttU, means for variably connecting said oscillation receiving device with turns nearest the end of said transt'orinm' connected to said condeusi and POttl'liliOl])(llOl', a relay ampliher having a control element and a plate, means For variably :l.f-7()(3l:illl,t f said control element with othcr turns o I. said transformer away from the end thereof coi'ulectcd to said potentioincter and condenser, said two means being iiiontrolled to provide variable i Illll ratios between the input circuit. including said oscillation receiving device and the output circuit including turns of said trans former, a varialiile condenss-n' permaucntty connected to said control element and said fixed condenser and potentiompter across the effective turns of the transformer but adapted to be variably associated with the winding of said transformer depending upon the connection of said control element with said. transformer, a second transformer having a Jun.

tuft

till] pair of windings, the primary winding of said transformer being connected to the anode of said relay amplifier, a variable condenser connected across the secondary Winding of said transformer for resonating the same, an audion tube having its control element connected to the secondary winding of said second transformer and adapted for detecting oscillations received by said oscillation receiving device.

Signed by me at Chicago, county of Cook and State of Illinois, this 10th day of November, 1924.

HIRAM D. CURRIER. 

